<nav class="navbar navbar-dark bg-primary">
  <div class="container-fluid">
    <a class="navbar-brand" href="{{ url_for('mall.product_list', page=1) }}">商品列表</a>
  </div>
  <div class="container-fluid">
    <a class="navbar-brand" href="{{ url_for('mall.product_add') }}">添加商品</a>
  </div>
</nav>